1. Field of the Invention
The present invention relates to devices for massaging shoulders and other parts of the human body to relieve stiffness.
2. Description of Related Art
Such massage devices are divided generally into those of the kneading ball type and the vibrator type. Known massage devices of the former type comprise a pair of opposite rotary plates arranged in a housing and rotatable in directions opposite to each other, and kneading balls mounted on the respective rotary plates eccentrically with respect to the axis of rotation of the plate with a connecting member provided between the ball and the plate (see, for example, Examined Japanese Patent Publication SHO 53-36275). Massage devices of the latter type heretofore known comprise a contact member attached to one end of a tubular body which can be held by one hand, and an electric motor housed in the contact member and having an eccentric weight (see Unexamined Japanese Patent Publication SHO 63-51862 or Examined Japanese Utility Model Publication SHO 44-12708).
The conventional device of the kneading ball type has the function of slowly massaging stiff parts with a great pressure, while the known device of the vibrator type has the function of gently massaging stiff parts by giving a vibration of high frequency. However, the known devices are not adapted to perform both functions at the same time.
It appears possible to incorporate an electric motor having an eccentric weight into the massage device of the kneading ball type between the ball and the connecting member for the device to selectively perform a kneading action and/or a vibratory action.
Nevertheless, if the conventional massage devices of the different types are merely combined into such a device, a vibratory force is imparted to the kneading ball which is originally adapted to exert a high pressure, so that when the neck, leg or like body part is held between the kneading balls, an excessive pressure is likely to act on the part to adversely affect the part. Moreover, the vibration of the eccentric weight between the kneading ball and the connecting member is transmitted through the connecting member to the interior of the housing to cause damage to the electric circuit and rotary plate support mechanism within the housing.